I've heard of Dr. Who and caught bits and pieces of the show. I have to admit, it never quite clicked with me or caught my attention enough to keep watching. I do really enjoy sci-fi and fantasy in general, though. Maybe I should give it a legit chance and sit down to watch a whole episode at some point.
I believe the Tardis is the phone booth they use to travel around. And Dr. Who is the main character. But I'd be hard-pressed to tell you more than that.
At my old job, my boss's husband used to sit around and watch marathons of the show. So I know there are plenty of hard-core fans out there.